FUEL INJECTION SYSTEM REGULATION slides.pptx

About vehicle fuel injection system types

1. FUEL INJECTION AND REGULATION

2. Fuel injection Fuel injection  is a system for admitting fuel into an internal combustion engine It has become the primary fuel delivery system used in automotive engines, having replaced   carburetors  during the 1980s and 1990s Difference between carburetors and fuel injection is Fuel injection atomizes the fuel through a small nozzle under high pressure Carburetor relies on suction created by intake air accelerated through a  Venturi tube to draw the fuel into the airstream

3. FUEL INJECTION TYPES THROTTLE BODY INJECTION (TBI) INJECTED ABOVE THROTTLE PLATES SINGLE INJECTOR CENTRAL PORT INJECTION (CFI) INJECTED ABOVE THROTTLE PLATES USUALLY MORE THAN ONE INJECTOR PORT FUEL INJECTION (PFI) INJECTORS IN INTAKE RUNNERS

4. Throttle Body Injection (TBI) First injection unit used Housing similar to Carb One or two injector One or two of these units mounted to intake manifold

5. TBI UNIT (SOMETIMES CALLED CFI) FIRST STEP FROM CARBURETORS SOME CARB CHARACTERISTICS LOW PRESSURE MOVEABLE PINTLE PRESSURE IS REGULATED SERVICEABLE FIG 6-40 CLASS

6. CENTRAL POINT INJECTION INJECTOR LOCATED IN LOWER HALF OF INTAKE MANIFOLD POPPET VALVES HIGH PRESSURE 60 PSI

7. Multi-Port Fuel Injection One injector per cylinder Mounts in intake manifold, sprays directly at intake valve Fired in groups or individually (SFI) Ram Tuning for denser air charge Lower A/F temps Leaner mixture during warm-up

8. PORT FUEL INJECTION INJECTS AT EACH CYLINDER HIGHER PRESSURE FED OFF OF FUEL RAIL MORE EFFICIENT OPERATION MODES MULTI-PORT SEQUENTIAL

9. Central Port Injection (CPI) Injector located in center of intake manifold 60 psi system 6 or 8 poppet valves attached to one TBI type injector

10. Central Multi-Port Injection (CMPI) Similar to CPI Individual injectors, with poppet valves

11. CONTINUOUS INJECTION SPRAYS ALL THE TIME MIXTURE CONTROL UNIT FUEL DISTRIBUTOR CONTROL PRESSURE REGULATOR

12. Fuel Pressure Regulator Located at end of fuel rail Maintains constant pressure at injectors Internal chamber contains a diaphragm Pressurized fuel on one side Manifold vacuum & spring tension on other Manifold vacuum pulls up on diaphragm, metering fuel that is returned to tank Excess fuel pressure can overcome spring tension, allowing fuel to return to tank Increases in manifold pressure causes spring tension to push diaphragm down, blocking return line, increasing pressure in rail.

13. Fuel Pressure Regulator

14. Fuel return Vacuum hose connection Fuel rail Fuel Pressure Regulator

15. FUEL PRESSURE REGULATOR Used on TBI systems Provides constant fuel supply Fuel pressure on one side Fuel pressure opens regulator under a certain pressure. Spring is calibrated

16. LOW PRESSURE FUEL INJECTOR 13-16 PSI TWO O-RINGS BALL PINTLE USED ON TBI AND CFI SYSTEMS MESH SCREEN EASY TO REPLACE

17. Poppet Nozzles Contains a check ball & extension spring Regulate the flow of fuel into cylinder Fuel flows when pressure exceeds 40 psi Ball reseats when pressure drops

18. INJECTOR TESTS ELECTRICAL OPERATION VOLTAGE SIGNALS SCOPE TESTING MECHANICIAL OPERATION PINTLE OPERATION BALANCE TEST FLOW

19. Injector Testing Coil Test – Specific current supplied, measures voltage drop Injector Balance – Inj. Energized for a precise time frame, record fuel pressure drop

20. Injector Circuit Testing Noise lights Simple test light that plugs into injector connector Light flashes with each electrical pulse

21. Injector Cleaning Periodic cleaning removes varnish & other deposits Pressurized canister dispenses cleaning solution MUST disconnect fuel pump

22. COMPONENT CHECKS AIR INDUCTION AIR FLOW SENSORS THROTTLE BODY FUEL SYSTEM CHECKS FUEL DELIVERY INJECTOR CHECKS INJECTOR CLEANING 6-61 LAB

23. Multiple carburator Multiple carburetors have more than one barrel Two barrel and four barrel configurations are commonly used to accommodate the higher air flow rate with large engine displacement Multi-barrel carburetors can have non-identical primary and secondary barrels of different sizes They are calibrated to deliver different air/fuel mixtures It can be actuated by the linkage or by engine vacuum in "progressive" fashion So that the secondary barrels do not begin to open until the primaries are almost completely open It maximizes airflow through the primary barrel(s) at most engine speeds, thereby maximizing the pressure "signal" from the Venturis , but reduces the restriction in airflow at high speeds by adding cross-sectional area for greater airflow

24. Electrical fuel injection Strict emission standards require precise fuel delivery Computers used to calculate fuel needs EFI very precise, reliable & cost effective EFI provide correct A/F ratio for all loads, speeds, & temp ranges

25. Electrical Fuel Injector Electromechanical device Controlled by PCM Engine rpm determines when injector opens How long it stays open determined by: Engine temp Engine load Throttle pos. O 2 sensor voltage

26. EFI EFI Multi port Injection System Injector is pressed into the runner( Port ) in the intake manifold. Injector sprays towards an engine intake valve. Each cylinder has it’s own injector EFI Direct fuel Injection System Injectors are pressed into the combustion chamber and spray fuel directly into the combustion chamber.

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